Scientists have discovered a four-layered structure hidden in the hippocampal CA1 region, which is one of the brain's main centers for memory, navigation and emotion.[1] Using advanced RNA imaging techniques, they mapped more than 330,000 genetic signals from tens of thousands of neurons.[1] Research has revealed sharp, shifting bands of cell types that run the length of the hippocampus.[1] This layered organization of the brain may help explain why different parts of CA1 support different behaviors.[1] The findings also suggest why some neurons break down more easily in disorders such as Alzheimer's disease and epilepsy.[1] This study provides new insights into the structure and function of one of the most important areas of the brain for human memory and cognitive processes.